Photographic developing paper



Oct. 15 1940. ALBERS ET AL 2,217,829

PHOTOGRAPHIC DEVELOP ING PAPER Filed Feb. 23, 1938 flw j EmulsionJensz'tb'zed with.

the dyectuffa of Exampde 1 Emu-uon senu'tzed with the dyestuffs of izamvde fligo 2 Emudu'ansensitized fizzy. 55

with the dyestuffs" of Example 3 [madden aensztzed vii-k /ze dyestuffs IA" of Ez m de 4 Fritz fldbers, frm'n Hubert Alfred Sack, 'h/dhedm desaien INVENTORS Waiter Dzietere, 064w? Rtest''r BY W THEIR ATTORNEYS PATENTOFFICE PHOTOGBAPHIO DEVELOPIN G PAPER Fritz Albers, Erwin Trabert,Alfred Sack, and Wilhelm Jessien,

Leverkusen-Wiesdori, Walter Dieterle, Dessau-Ziebigk, and Oskarlh'ester, Dessau, Germany, assignors, by mesne assignments, to GeneralAniline & Film Corporation, New York, N. Y., a corporation oi Delawareapplication February 23, 1938, Serial No. 192,066

In Ge many Claims.

This invention relates to an improved photographic developing printingpaper comprising sensitized silverchloride emulsions andsilverchlorobromide emulsions with or without an ad- 6 dition ofsilveriodide. Some of these emulsions are cast after washing and somewithout washing. For adjusting the sensitivity and gradation variousingredients, conditions of ripening and additions are used. Increase ofsensitivity in such positive emulsions is limited in consequence of theincreasing coarseness of grain and danger of fog which accompanyincreased ripening. Increasing the sensitivity by the addition ofchemical sensitizers has only attained importance in the copying processand is not generally applicable to the more highly sensitive developingemulsions in consequenceof danger of fog, diminution of durability andother disadvantages. 0ptically sensitized emulsions have also been usedfor making photographic papers for special purposes, for example forcopying documents and as material for copying by reflection, as well asfor color photography. In consequence of their sensitivity togreen-yellow, yellow or red light, "such papers cannot be treated in themanner usual for copying purposes in yellow light, and are thus excludedas developing papers in the copying art.

It is the object of this invention to increase the general sensitivityof the paper emulsion by adding to the latter anoxothiazolinocarbocyanine which extends the region of spectralsensitivity only in such a manner that it is possible to use an intensegreen or yellow darkroom light. It is advantageous to use a dye whichproduces a steep fall of the spectral curve of sensitivity towards thelonger waves of the visible spectrum. These dyestuffs also have theproperty that they can be easily removed from the photographic layer sothat the picture shows clear whites.

The accompanying self-explanatory drawing illustrates the sensitivitycurves of the emulsions of the following examples.

The following dyestufis are examples of those suitable for theinvention:

March 3, 1937 I g cikon-cikL f oini I 1m A. U. Sensitivity maximum onsilverchloride or silverchlorobromide 5000 Sensitivity extension up to5200 (a) O SEH: 0310 CH CH l N can I (um A.U. Sensitivity maximum onsilverchloride or silverchlorobromide 4950 Sensitivity extension up to5150 0 s-cm J-on=cn-cn CaHl I 1 CzHs cm A. U. Sensitivity maximum onsilverchloride or silverchlorobromide 5050 Sensitivity extension up to5250 These dyestuffs are made in known manner, for example by theprocess described in-British specification 353,863 accepted July 24,1931.

.Photographic papers prepared by this invention may be treated in adarkroom lighted with green or yellow light, for instance light whichhas passed through Agfa filter No. 113 or No. 112.

The preparation of gelatine silver bromochloride emulsion is well knownto those skilled in the photographic art. To sensitize such emulsionswith the dyes herein described, there is prepared a stock solution ofthe dye by dissolving it in a suitable alcohol, such as methylalcohol.Then into one liter of a developing photographic printing emulsion thereis incorporated an amount of the above stock solution (diluted somewhatwith water, if desired) containing from approximately 0.03 to about 0.01gram of the desired dye. This sensitized emulsion may then be coatedupon a suitable paper to a suitable thickness and allowed to dry, thedetails of which are well known to photographic experts. Photographicprinting papers so sensitized have properties different from onesheretofore produced by well known methods and hence are of specialutility. Furthermore it will be apparent that these dyes may beincorporated in the emulsion by other methods practiced by the art as,for instance, by bathing the paper upon which the emulsion has beencoated in a solution of the dye in an appropriate solvent.

We claim:

1. Photographic developing printing paper capable of being copied inintense green or yellow dark room light without fogging comprising agelatin emulsion layer containing a member selected from the groupconsisting of silverchloride, silverchlorobromide, silverchloroiodideand silverchlorobromoiodide, and an oxothiazolino trimethinecyanine dye.

2. Photographic developing printing paper capable of being copied inintense green or yellow dark room light without fogging comprising agelatin emulsion layer containing a member selected from the groupconsisting of silverchloride, silverchlorobromide, silverchloroiodideand silverchlorobromoiodide, and an oxothiazolino trimethinecyanine dyecapable of producing a steep fall of the spectral curve of sensitivitytowards the longer waves of the visible spectrum.

3. Photographic developing printing paper capable of being copied inintense green or yellow dark room light without fogging comprising agelatin emulsion layer containing a member selected from the groupconsisting of silverchloride, silverchlorobromide, silverchloroiodideand silverchlorobromoiodide and a dye corresponding with the followingformula alkyl in which X represents an acid radical.

4. Photographic developin printing paper capable of being copied inintense green or yellow dark room light without fogging comprising agelatin emulsion layer containing a member selected from the groupconsisting of silver chloride, silverchlorobromide, silverchloroiodideand silverchlorobromoiodide and a dye corresponding with the followingformula in which X represents an acid radical.

FRITZ ALBERS. ERWIN TRABERT. ALFRED SACK. WILHELM JESSIEN. WALTERDIETERLE. OSKAR RIESTER.

